Drill pipe monitoring systems

ABSTRACT

Disclosed is a system for monitoring the speed at which a pipe string is lowered into or pulled out of a well bore during a well drilling operation. The system includes a unit which derives an electrical signal as a function of instantaneous pipe speed and a monitoring system which compares signals representative of instantaneous velocities with respect to predetermined velocity limits and provides physiological indications whenever such limits are transgressed. Also included are visual indicator means and recorder means, as well as a loop control system for automatic regulation of the speed.

United States Patent 1 1 3,866,468

Smith et al.

[ Feb. 18, 1975 [54] DRILL PIPE MONITORING SYSTEMS 3,465,326 9/1969 Weiret al. 324/161 X Inventors: Hubert Irvin Smith; Fred L. on, 3,638,4852/1972 Knauth 73/155 both of Houston Primary E.\'aminer.lerry W. Myracle[73] Assignee: Drill-Au-Mation, Inc., Houston,

Tex. [57] ABSTRACT 22 Filed; Oct 4 1972 Disclosed is a system formonitoring the speed at which a pipe string is lowered into or pulledout of a [21] App! 2943 well bore during a well drilling operation. Thesystem includes a unit which derives an electrical signal as a [52] US.Cl. 73/151 function of instantaneQuS P Speed and "wnlwring [51] Int. Cl.E2lb 47/00 System which compares SigmllS rcpresenmtiv of 5 Field fSearch 73 5 152 515; stantaneous velocities with respect topredetermined 1 250; 75 40; 24 1 velocity limits and providesphysiological indications whenever such limits are transgressed. Alsoincluded [56] References Cited are visual indicator means and recordermeans, as well UNITED STATES PATENTS as a loop control system forautomatic regulation of 2447208 8/1948 Rendel 324/161 x the Speed3382,713 5/1968 Chutter 73/151 14 Claims, 4 Drawing Figures PATENTED FEBI 8l975 SHEET 1 or 2 SHEET 2 OF 2 Iutim DRILL PIPE MONITORING SYSTEMSBACKGROUND OF THE INVENTION This invention pertains to methods andapparatus for monitoring and deriving indications of the speed at whicha pipe string travels while such pipe string is lowered into or pulledout of a well bore during a well drilling operation.

In a rotary well drilling operation, a drilling bit at the end of adrill string or pipe is rotated to cut into the earth formations. Thedrill string or string of pipe is made up of pipe joints, usually aboutfeet in length, which are coupled to one another by threaded tooljoints. As the well is drilled, additional pipe joints are added to thestring of pipe.

From time to time during A rotary drilling operation, the drill stringor pipe is removed, for example, to change the bit or to perform anotheroperation, such as obtaining a log of the formations. Thereafter, thepipe is returned to continue drilling or to run a string of casing intothe hole. The process of removing and reinserting a string of pipe iscalled tripping".

in removing or re-inserting a pipe string, the pipe joints aresuccessively un-coupled or coupled as the case may be and the sectionsof pipe or joint sections are stacked in the drilling rig. Usually, pipejoints are interconnected lengths of two or three pipe joint sections,sometimes referred to a doubles and Thribbles or pipe stands when theyare vertically stacked in the drilling rig. In this relationship, thepipe joints also are said to be racked in the derrick. I

The drilling rig has a device called a rotary table which is used torotate the drilling string. In the rotary table on the derrick floor ofthe rig are releasable slips which are used to releaseably support thepipe string in the borehole during the tripping operation. For example,while going in with a pipe string, the slips serve to hold the upper endof the pipe string in the rotary table and prevent the pipe string fromdropping into the well. A vertically movable traveling block in the rigderrick is used to bring a double or thribble pipelength or stand into aposition where such a stand can be theadedly coupled to the upper end ofthe pipe supported in the rotary table. Upon interconnection of a pipestand to the pipe string, the slips are released and the traveling blocksupports and lowers the string of pipe into the well bore until theupper end is just above the slips, whereupon the slips in the rotarytable are re-engaged with the pipe string. This operation is continueduntil the bit at the lower end of the pipe string is in drillingposition. From the time that the pipe string begins its motion from astop or rest position, it first accelerates to a running-in speed whichis essentially a constant speed, and then it decelerates to a stoppedcondition.

Typically, in well drilling operations a drilling fluid (commonly calledmud") is used where the functions and properties of the drilling fluidare intended to promote a safe and speedy drilling and completion of thewell. While the pipe string is being moved into the bore hole or from abore hole, hydraulic effects or pressure surges relative to the boreholeare created which can damage the subsequent productivity ofhydrocarbonbearing formations. Excessive surge pressure can also lead toloss of drilling fluid through pressure induced fractures of theformation which can cause sticking of the drill pipe, excessive loss ofmud and other complications.

When the pipe is removed from the borehole, the above describedprocedure is reversed in that the pipe joints are racked in the derrickas double or triple stands as they are successively uncoupled from thestring of pipe. During the pipe removal operation, the motion of thepipe is first an acceleration to a constant speed and then decelerationto a stop condition. While coming out of the borehole, if the string ofpipe is pulled too fast while being removed,'acondition known asswabbing and other undesirable hydraulic effects can occur. Swabbing isa condition involving a reduction in the total hydraulic pressure in theholeto a less than normal pressure for the hydrostatic pressure of thestatic drilling fluid column in the well bore. An excessive reduction inhydraulic pressure can cause the well to kick, that is, formation fluidsunder their in-situ pressures may enter into the drilling fluid and intothe well bore. This action could cause a blow out." In soft formations,collapse of the borehole walls can also occur because of swabbingeffects.

Swab and surge pressures can be minimized by reducing the viscositycharateristics of the drilling fluid, providing adequate borehole topipe clearances, and minimizing flow constrictions in the pipe string.These factors are considered and taken into account when planning thedrilling operations for a well. While a round trip of the pipe string isbeing made, however, these pressures can only be controlled by drillerin control of the pipe speed. Commonly, a listing or schedule withoptimum velocities in terms of information such as pull 10 stands atseconds per stand etc. is available for use by the driller. Thisschedule can be computed by hand or by a computer. The driller will thenattempt to pull or run the pipe string at a uniform velocity by notingthe total time required for moving one stand or a joint of pipe over agiven distance. However, the driller cannot give undivided attention tothe pipe speed requirements because he must be attentive to the actionsof his other crew members in the synchronized operation of moving a pipestring as well as the other equipment under his control.

The schedule, however, cannot always take into considerationmiscellaneous factors, which sometime affect velocity, such as theamount of drag on the moving pipe, the position of the hoistingequipment and the behavior of the machinery. Moreover, even if theoperation follows the schedule and average speed is within theprescribed limits, it is possible for the instantaneous speeds to beexcessive and cause damage.

If the driller simply pulls or runs the pipe very slowly, the hydraulicpressures can be controlled but this is undesirable since it is costlyin terms of rig time consumed and-furthermore, excessive time periodswithout mud circulation (as when tripping) may lead to various welldifficulties. it should be noted that an optimum velocity varies as afunction of the amount of moving pipe in the hole, generally, but notnecessarily, decreasing with increasing lengths of moving pipe.

It should be appreciated from the foregoing that tripping the pipe is asynchronized operation of the drilling crew to move the pipe into or outof the borehole in as short a time as possible, not only to reduce costsbut also to reduce the risks involved in not having the pipe in the holewhere mud control can be maintained. As noted heretofore, the technologyto date for the driller to determine proper run-in or run-out speeds ofa string of pipe involves only rudimentary execution procedures based onthe elapsed time for moving a section of pipe. A stop watch is sometimesused as the determinant for the velocity, and it will be appreciatedthat this can only establish average values for velocities. Thistechnique has the very obvious disadvantage that excessive velocitiesmay occur even though the average velocity is kept within limits and theimprecisencss of the operation can unknowingly cause well damage.

SUMMARY OF THE PRESENT INVENTION By means of the present invention apreselected or desired velocity range for moving the pipe can beestablished and the instantaneous pipe speed monitored relative to thevelocity range so that the driller can optimize the speed of theoperation while eliminating or minimizing the risks of excessive speeds.This is accomplished by apparatus which includes means for deriving anindication of the instantaneous speed or velocity of the pipe in termsof an electrical signal and means for comparing the electrical signalrelative to preset signal values for providing an output indicationwhenever velocity limits are exceeded. The system is further providedwith means for selectively limiting effective operation of the system tomovement of the pipe in one direction, and means for dropping out thealarm indicator upon stopping of the pipe.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention may be moreeasily understood and will become more apparent from the followingdescription when taken in conjunction with the drawings, in which:

FIG. 1 is a schematic illustration of a drilling system for drilling awell bore,

FIG. 2 is an electrical schematic diagram of the system embodying thepresent invention,

FIG. 3 is a partial view in cross-section of a drum for a drilling lineon a drawworks, and

FIG. 4 is a schematic illustration of another type of drilling systemcontrol.

DESCRIPTION OF THE PREFERRED EMBODIMENT The tripping of a pipe stringrelative to a well bore should be accomplished in the shortest possibletime without causing damage to the well or creating hazardousconditions. With the known parameters of the well, safe maximum velocityvalues for moving the pipe can be defined. Minimum velocities, ofcourse, do not of themselves create problems, but in the tripping of thewell a certain rhythmical operation is developed between the variousoperators. The judgement of the hoist operator who controls speed of thepipe string is assisted if both the upper and lower velocity limits aredefined so that he can maintain an established or defined rhythmicaltime operation relative to movement of the pipe.

Referring now to FIG. 1, there is shown a well that traverses earthformations 10. The well is illustrated as having surface casing 11 forthe first few hundred feet and a protective-liner 12 set in place in thenext, lower section. The drilling of the well is accomplished by meansof a conventional rotary bit 13 attached to a drilling string 14. Thedrill string 14 extends to the earths surface where it passes throughconventional well head equipment 15 that includes blowout preventers andother well-known equipment. The drill string 14 is rotated by means of arotary table 16 in a rig derrick 17. On the derrick 17 one threbblesection of pipe 18 is illustrated for purposes of explanation. When thepipe string 14 is being pulled from the well bore, slips 19 on therotary table suspend and support the pipe string in the borehole whilethe pipe section 18, which is uncoupled from the string, is placed inthe pipe rack. In making a trip, elevators 20 are used for latching ontoor gripping the pipe string. The elevators 20 are attached to atraveling block 21 which is coupled by a drilling line 22 to a drawworks23. The drilling line 22 is suspended in the center of the rig near theapex by a crown block 24.

The operation for removing a string of pipe from a wellbore starts bythe driller releasing the drawworks 23 and lowering the elevators 20 tothe derrick floor 17. There the crew (sometimes called roughnecks) latchthe elevators 20 to the protruding stand of the string of pipe. Thedriller opens the throttle on the drawworks 23, releases the drawworksbrakes, and the drill pipe is on its way up. The driller stops theupward movement of the traveling block 21 when the elevators 20 carrythe pipe up to a derrickman positioned above the drilling rig floor anda joint connection is above the table 16. The slips 19 are then set bythe crew on the derrick floor and the crew uses tongs to uncouple a pipesection. Upon disconnection of the pipe section, the bottom of thedisconnected stand of pipe is placed on the rig floor while thederrickman swings the top of the stand of pipe into the derrick piperack. As soon as the derrickman has control of the upper end of the pipestand, the elevators 20 are released from the pipe string so that thetraveling block 21 and elevators 20 can be lowered at full speed to therig floor. This operation is repeated until all of the pipe string isremoved from the well bore.

For returning the pipe to the well bore, the foregoing describedoperations are simply reversed. This is, the elevators 20 pick up theupper end of a stand of pipe which is racked in the rig, and the crewcouples the stand of pipe to the pipe string supported by the slips 19.The slips 19 are then released and the pipe string lowered into theborehole. When the upper end of the pipe string is just above the rotarytable, the slips 19 are again set. The elevators 20 are next releasedand the traveling block raised to pick up the upper end of another standof pipe and the operation is repeated.

Referring now to FIG. 2, there is a schematic illustration of a systemwhich includes a sensor 30 for detecting speed from a drawworks andproducing electrical signals as a function of the speed. The sensor 30illustrated involves a tooth gear 31 which can have magneticallysusceptible teeth and a pick-up coil 32. The gear 31 can be coupled tothe drilling line drum so that the electrical pulse output of pick-upcoil 32, as a function of time, is indicative of the speed. The pulsesignal 8;, is supplied to an electrical tachometer 34 which includes aconverter 33. The converter 33 converts the pulse signal S to a directcurrent voltage signal S where the level of the signal is a function ofthe electrical pulse input rate. An alternate embodiment would provideD.C. voltage signal, from a DC. generator in lieu of pulse device 30 andpulse converter 33. The voltage signal S provides one input to acomputation circuit 61. The circuit 61 also receives a reference inputvoltage signal S from a voltage source (not shown). The signal Sprovides a preset or preselected electrical signal representative of adesired speed. The computation circuit 61 subtracts the voltage value ofthe signal S from the voltage value for the signal S and divides by thevoltage value for the signal S The computation produces an output signalS, which is a per centage function of the velocity deviation. Thisoutput signal S, is supplied to an indicating meter 62; thus anindication of how much the velocity deviation is in terms of percentageis defined by meter 61. The voltage signals 8, and S are also supplieddirectly to pens in a recorder 60 for a direct recording of theirindependent values.

The percentage deviation output signal S, from the computation circuit61 also is supplied via the comparator circuits 61a and 61b to thesolenoid coils 35 and 37 of the alarm relays 36 and 38. The high and lowpercentage deviations at which the alarm relays 36 and 38 are energizedare individually selectable and adjustable by potentiometer means 62aand 62b. If the detected speed is excessive and the corresponding Ssignal exceeds the S signal by the preselected percentage, the relayswitch 36 is energized. If the detected speed is too slow and thecorresponding S signal is less than the S signal by the secondpreselected percentage, the relay switch 38 is energized.

The system for indicating the occurrence of excessive speed includes afirst horn and light indicator set where the horn 39 and light 40 areelectrically coupled in a parallel relationship. An input for the horn39 and light 40 is coupled to the normally open contact 41 of the relayswitch 36. Thus, when the solenoid coil 35 of the relay is actuated, therelay 36 is operated and electrical power at a movable contact 42 can beapplied to the horn 39 and light 40 and result in an indication of theoccurrence of excessive speed.

A second horn and light indicator setincludes a horn 43 and light 44electrically coupled in a parallel relationship. One input for the horn43 and the light 44 is coupled to the normally open contact 45 of therelay switch 38. Thus, when the solenoid coil 37 and the relay switch 38operate, electrical power at a movable contact 46 can be applied to thehorn and light set for an indication of too-slow speed.

The relay system includes the relay switch 38 which has its movablecontact 46 normally closed with a contact 47 coupled to a light means 48which is grounded. Illumination of the light means 48 is indicative ofnormal operation within the speed limits. The movable contact 46 of therelay switch 38 is coupled to a stationary contact 49 of the relayswitch 36 so that if the velocity is not too great, the movable contact42 normally closes with the stationary contact 49. The movable contact42 of the relay switch 36 is coupled to a stationary contact 50 of apressure responsive switch 51. The pressure responsive switch 51normally closes a movable contact 52 with the stationary contact 50 whenthe drill line carries the pipe load and normally opens the contacts 50and 52 when the traveling block is free of the load. The movable contact52 is, in turn, coupled to a movable contact 53 of a voltage sensitiverelay 54. The stationary contact 55 of the voltage sensitive relay iscoupled via an on-off switch 56 to a source of direct current 57.

The electrical output of the converter 33 is coupled to the solenoidcoil 58 of the voltage sensitive relay 54 so that when the speeddecreases to a low value, the corresponding voltage signal S isinsufficient to keep the relay actuated and the relay switch will open.The output of the converter 33 is also coupled via a switch contact set59 to the drive system (X) of the recorder 60. Thus, when the pressureswitch 51 is operated, the recorder drive is actuated and the strip orother chart in the recorder is moved as a function oftime. Also includedin the pressure responsive switch 51 are a set of contacts 62a which,when closed, provide electrical continuity between the computationcircuit 61 and the meter 62. Thus, meter 62 is operated only when thepressure switch 51 is operated.

in the operation of the foregoing system, the on-off switch 56 is firstoperated. The drawworks 23 will produce a signal to the converter 33 foreither direction of movement and when the speed produces the electricalsignal, the voltage sensitive relay 54 is actuated. If the pipe isattached to the line, i.e., there is a load on the drilling line, thenthe pressure switch 51 will condition the indicator circuits foroperation. If there is no load and the empty blocks are travelingbetween locations, the switch 51 will prevent the indicators fromoperating.

Assuming a pipe load which is being transported by the traveling blockso that switches 54 and 51 are actuated, then power is normally appliedfrom the source 57 through switch 36 and 38 to the indicator light 48.Operation of the light 48 is indicative of a normal operation.

The speed signal S from the converter 33 is applied to the recorder 60and to the computation circuit 61. The computation circuit 61 issupplied with a reference signal S which is representative of thedesired speed. The alarm comparator circuits 61a and 61b are preset toany desired low or high deviation from the desired speed and wheneverthe preset values are transgressed either the solenoid coil 35 or thesolenoid coil 37 receives a control signal. If solenoid coil 35 isenergized because the velocity signal S is too low then power fromsource 57 is applied via the relay switch 36 to the horn 39 and thelight 40. On the other hand, if the solenoid coil 37 is energized, thenswitch 38 applies electrical power from the power source 57 via theswitch 38 to the horn 43 and light 44.

It will be readily apparent that while the traveling blockisdecelerating to a stopped position, this will usually cause the meterto traverse the low velocity limit. To eliminate the nuisance ofreceiving the physiological indications each time that this eventoccurs, the switch relay 53 is set for a drop out value to disconnectthe light and horn sets whenever the signal reaches a predeterminedlower value. This value will correspond to a slower average speed usedwhen actually handling the pipe.

The foregoing described system is, of course, susceptible tomodifications. The tachometer 34, comprised of converter 33, computationcircuit 61, and the alarm comparator circuit 61a and 61b, as describedin manufactured and distributed commercially. A differential tachometerwhich is referred to as dynalco DT series can be used and will acceptpulse-type inputs. The pressure switch 51 can be applied and used on thedrill line, the weight indicator or other suitable and appropriatelocations. The signal S can be supplied by a computer or by a manuallyadjustable device. The recorder 60 may be continuously driven on astraight time base. On the footage basis, as illustrated, a variablespeed motor in the recorder would be powered by the speed or velocityvoltage signal.

In FIG. 3, which is a partial illustration of a drilling line drum ofthe drawworks 23, there is disposed along a flange 26 of the drum aroller 27 which is attached to a transducer device 28. The rotationalmotion of the flange 26 through a friction drive rotates the roller 27and, in turn, transducer 28 produces an electrical output signal as afunction of the rotation of roller 27. The rotation of roller 27 and theoutput signal oftransducer 28 is a function of velocity of the drillingline which is a function of the speed of the pipe. Transducer 28 may beconstructed and adapted to provide a direct current signal where thepolarity is dependent upon the direction of rotation of roller 27, inwhich case a double pole, double throw polarity reversing switch 128 isnecessary to provide a positive input voltage S,. However, switch 128 isnot required if transducer 28 provides a non-direction-dependent voltagesignal, such as a pulse type signal. The magnitude of the signal fromtransducer 28, which varies as a function of speed, is affected by thelocation of the wheel 27 relative to the axis of the drum, the size ofwheel 27 and a number of other factors. All of these factors can beelectrically compensated so that a signal proportional to the speed orvelocity of the drilling line can be obtained. Thus, an analog signalcan be derived directly from this type of pick-up or sensor.

Referring now to FIG. 4, a system is illustrated for automatic control.In this system, the speed of the pipe travel is also proportioned fromthe drawworks 23 which provides a drive of a sensor 65. The sensor 65 isa transducer which provides electrical output signals S, calibrated interms of instantaneous pipe speed. The drawworks 23 is powered by anengine means 69 which can be speeded up or slowed down to regulate thepipe speed by means of a throttle control. The throttle control isregulatable and controlled proportionately to an input electrical signal8,. An electrical controller means 66 is provided which is arranged tocompare input electrical signals S to a preselected reference signalvalue S and provide a compensating control signal S, whenever S, and Sdiffer by a predetermined value.

The reference electrical signal S can be generated by a computer means68 which is suitably programmed to calculate the optimum speed andprovide a corresponding electrical signal S As a further controlmeasure, a flow meter 67 can be coupled into the mud return line toprovide an electrical signal O which is representative ofthe flow rate.The Q signal would be used to decrease the S signal value in the eventthe bit becomes clogged with materials in the borehole or shouldexcessive mud line pressures occur for any other reason. Of course, adecrease S signal will decrease the speed of the pipe movement.

The foregoing description of the system which involves control of thethrottle principally achieves the control of speed while coming out ofthe hole with the pipe string. While going in the hole, the controlsignal 5., would be applied to the drawworks brake control systems.

While particular embodiments of the present invention have been shownand described, it is apparent that changes and modifications may be madewithout departing from this invention in its broader aspects; and,therefore, the aim in the appended claims is to cover all such changesand modifications as fall within the true spirit and scope of thisinvention.

What is claimed is:

1. A method for monitoring the speed-of pipe relative to a well borecomprising the steps of:

producing a first electrical signal as a function of the actual speed ofthe pipe as it moves relative to a well bore,

producing a second electrical signal as a function of a desired speedvalue, comparing said first and second electrical signals and producingat least one electrical output signal as a function of thepre-established difference between said first and second electricalsignals, and applying said one output signal to an alarm means.

2. The method of claim 1 and wherein said first electrical signal isproduced for only one direction of the pipe.

3. Alarm means for a drilling system for providing an indicationwhenever predetermined linear speed values for travel of a pipe stringrelative to a borehole are exceeded by the actual speed of pipe beingmoved relative to a borehole where the drilling system includes meansfor moving a pipe string linearly relative to a borehole, and means forproducing electrical input signals representative of actual linear speedof a pipe being moved relative to a borehole,

said alarm means including selectively operable preset means forestablishing an electrical preset condition which is representative of alinear speed limit, means for receiving and correlating said electricalinput signals to said preset means where such input signals arerepresentative of actual linear speed of a pipe being moved relative toa borehole, said correlating means being constructed and arranged forproviding output signals whenever such an input signal reaches saidelectrical preset condition, and

means for receiving said output signals and for producing aphysiological indication in response thereto.

4. The apparatus of claim 3 wherein said preset means and saidcorrelating means include current comparison means which are adapted forreceiving a reference electrical current signal representative of adesired predetermined speed limit and for receiving electrical inputsignals as electrical currents for comparison of a reference signal tosuch input signals, said current comparison means being constructed andarranged for response to such reference signal and such input signalsfor producing first output electrical signals whenever a deviation ofthe electrical current of such input signals from the electrical currentof such reference signal exceeds a predetermined current value and forproducing second output electrical signals whenever a deviation of theelectrical current of such input signals from the electrical current ofsuch reference signal is below a predetermined current value.

5. The alarm means of claim 4 and further including means for receivingsuch reference signal and said input signals for determining thepercentage of deviation of the actual speed of a pipe being movedrelative to a borehole to the preset electrical condition.

6. The apparatus of claim 4 and further including means for selectivelyenabling said alarm means, said enabling means being connectable to adrilling system and to said alarm indication means and including meansfor response to movement of pipe in a given direction relative to aborehole for operating said selectively enabling means.

7. In an alarm system for use with a drilling system and for monitoringthe speed of a pipe string while it is being run into or out of a wellbore, means for moving a pipe string linearly relative to a borehole,and means for producing electrical input signals representative ofactual linear speed of a pipe being moved relative to a borehole,

comparison means for receiving electrical input signals which areproportional to an instantaneous speed of a pipe string during movementthrough a borehole and for receiving a preset electrical signalproportional to a predetermined speed of pipe movement, said comparisonmeans being constructed and arranged for comparing such electricalsignals to such present electrical signal for providing outputelectrical signals whenever such input signals deviate relative to suchpreset electrical signal in excess of a predetermined value, alarm meansfor producing alarm indications, and means coupled to said alarm meansand said comparison means and responsive to the occurrence of suchoutput signals for actuating said alarm means.

8. The alarm system of claim 7 wherein said comparison means isconstructed and arranged for producing output signals which arerepresentative of a difference between an input signal and a presetsignal value, and said alarm system further includes means for dividingsuch output signals by the value of an input signal to determine apercentage of deviation.

9. The alarm system of claim 7 wherein said comparison means isconstructed and arranged for producing said output signals as firstoutput signals for pipe movement at speed values at a predetermineddeviation greater than said preset signal and as second output signalsfor pipe movement at speed values at a predetermined deviation less thansaid preset signal,

said alarm means including first and second separate alarm indicatorsresponsive to output signals for providing an alarm indication,

said first and second alarm indicators respectively being coupled tosaid comparison means and respectively operative in response to saidfirst and second output signals.

10. The alarm system of claim 9 and further including visual indicatormeans, and means responsive to said first output signals for selectivelysupplying an actuating signal to said indicator means whenever saidinput signals are within the limits of said predetermined deviations,said supplying means being responsive to said first output signals fordisconnecting said actuating signals from said first indicator means andfor applying said actuating signals to said-first alarm means and re--sponsive to said second output signals for disconnecting said actuatingsignals from said second indicator means and for applying said actuatingsignals to said second alarm means.

11. The alarm system of claim 10 and further including means constructedand arranged for response to direction of travel of the pipe relative toa borehole for actuating said supplying means only for one direction oftravel.

12. A system for use with a drilling system in moni-. toring the speedof a pipe string while it is being run into or out of a well bore,comprising:

transducer means constructed and arranged for translating the linearspeed of a pipe string being moved by traveling block means into adirect current electrical input signal representative of such 5 speed,

traveling block means for moving a pipe means linearly with respect to aborehole, comparison means coupled to said transducer means forreceiving the input signals from said transducer means for comparingsuch signals to a preset electrical signal value in said comparisonmeans for providing first output signals whenever such input signals arebelow said preset signal value by a predetermined magnitude or secondoutput signals whenever such input signals are above said preset signalby a predetermined magnitude, first and second alarm indicator meanscoupled to said comparison means for receiving respectively such firstand second output signals and for producing an indication in response toan output signal. 13. Apparatus for use in a drilling system where astring of pipe is moved into or out of a borehole, said apparatusincluding means for producing input electrical signals as a function ofthe actual linear speed of a string of pipe moved relative to aborehole,

means for moving a string of pipe linearly relative to a borehole,

alarm means coupled to said input electrical signal means for providingan indication whenever a string of pipe is moved relative to a boreholewith an actual linear speed which exceeds a predetermined linear speedlimit value,

said alarm means including preset means for selectively establishing apredetermined linear speed limit value by selective adjustment of anelectrical parameter in said alarm means,

means for correlating input electrical signals from said inputelectrical signal means to such electrical parameter in said alarm meansand for providing output electrical signals whenever such inputelectrical signals and such preset electrical parameter in said presetmeans reach a predetermined correlation, and

means coupled to said correlating means for receiving said outputsignals and for producing a physiological indication in responsethereto.

14. A system for use in a drilling system for monitor- 50 ing the speedof a pipe string while it is being run into or out of a well bore,comprising:

transducer means constructed and arranged for translating the linearspeed of a pipe string being moved by traveling block means into directcurrent electrical input signals representative of such speed,

traveling block means for moving a string of pipe relative to aborehole,

electrical comparison means for receiving input signals from saidtransducer means and for comparing such signals to a preset electricalsignal value and for providing first output signals whenever said inputsignals are less than said preset signal by a predetermined magnitudeand for providing second output signals whenever said input signals aregreater than said preset signal by a predetermined magnitude,

termined magnitude, and

said supplying means being actuatable by said first output signal forsupplying an actuating signal to said first alarm means and beingactuatable by said second output signal for supplying an actuatingsignal to said second alarm means.

1. A method for monitoring the speed of pipe relative to a well borecomprising the steps of: producing a first electrical signal as afunction of the actual speed of the pipe as it moves relative to a wellbore, producing a second electrical signal as a function of a desiredspeed value, comparing said first and second electrical signals andproducing at least one electrical output signal as a function of thepreestablished difference between said first and second electricalsignals, and applying said one output signal to an alarm means.
 2. Themethod of claim 1 and wherein said first electrical signal is producedfor only one direction of the pipe.
 3. Alarm means for a drilling systemfor providing an indication whenever predetermined linear speed valuesfor travel of a pipe string relative to a borehole are exceeded by theactual speed of pipe being moved relative to a borehole where thedrilling system includes means for moving a pipe string linearlyrelative to a borehole, and means for producing electrical input signalsrepresentative of actual linear speed of a pipe being moved relative toa borehole, said alarm means including selectively operable preset meansfor establishing an electrical preset condition which is representativeof a linear speed limit, means for receiving and correlating saidelectrical input signals to said preset means where such input signalsare representative of actual linear speed of a pipe being moved relativeto a borehole, said correlating means being constructed and arranged forproviding output signals whenever such an input signal reaches saidelectrical preset condition, and means for receiving said output signalsand for producing a physiological indication in response thereto.
 4. Theapparatus of claim 3 wherein said preset means and said correlatingmeans include current comparison means which are adapted for receiving areference electrical current signal representative of a desiredpredetermined speed limit and for receiving electrical input signals aselectrical currents for comparison of a reference signal to such inputsignals, said current comparison means being constructed and arrangedfor response to such reference signal and such input signals forproducing first output electrical signals whenever a deviation of theelectrical current of such input signals from the electrical current ofsuch reference signal exceeds a predetermined current value and forproducing second output electrical signals whenever a deviation of theelectrical current of such input signals from the electrical current ofsuch reference signal is below a predetermined current value.
 5. Thealarm means of claim 4 and further including means for receiving suchreference signal and said input signals for determining the percentageof deviation of the actual speed of a pipe being moved relative to aborehole to the preset electrical condition.
 6. The apparatus of claim 4and further including means for selectively enabling said alarm means,said enabling means being connectable to a drilling system and to saidalarm indication means and including means for response to movement ofpipe in a given direction relative to a borehole for operating saidselectively enabling means.
 7. In an alarm system for use with adrilling system and for monitoring the speed of a pipe string while itis being run into or out of a well bore, means for moving a pipe stringlinearly relative to a borehole, and means for producing electricalinput signals representative of actual linear speed of a pipe beingmoved relative to a borehole, comparison means for receiving electricalinput signals which are proportional to an instantaneous speed of a pipestring during movement through a borehole and for receiving a presetelectrical signal proportional to a predetermined speed of pipemovement, said comparison means being constructed and arranged forcomparing such electrical signals to such present electrical signal forproviding output electrical signals whenever such input signals deviaterelative to such preset electrical signal in excess of a predeterminedvalue, alarm means for producing alarm indications, and means coupled tosaid alarm means and said comparison means and responsive to theoccurrence of such output signals for actuating said alarm means.
 8. Thealarm system of claim 7 wherein said comparison means is constructed andarranged for producing output signals which are representative of adifference between an input signal and a preset signal value, and saidalarm system further includes means for dividing such output signals bythe value of an input signal to determine a percentage of deviation. 9.The alarm system of claim 7 wherein said comparison means is constructedand arranged for producing said output signals as first output signalsfor pipe movement at speed values at a predetermined deviation greaterthan said preset signal and as second output signals for pipe movementat speed values at a predetermined deviation less than said presetsignal, said alarm means including first and second separate alarmindicators responsive to output signals for providing an alarmindication, said first and second alarm indicators respectively beingcoupled to said comparison means and respectively operative in responseto said first and second output signals.
 10. The alarm system of claim 9and further including visual indicator means, and means responsive tosaid first output signals for selectively supplying an actuating signalto said indicator means whenever said input signals are within thelimits of said predetermined deviations, said supplying means beingresponsive to said first output signals for disconnecting said actuatingsignals from said first indicator means and for applying said actuatingsignals to said first alarm means and responsive to said second outputsignals for disconnecting said actuating signals from said secondindicator means and for applying said actuatinG signals to said secondalarm means.
 11. The alarm system of claim 10 and further includingmeans constructed and arranged for response to direction of travel ofthe pipe relative to a borehole for actuating said supplying means onlyfor one direction of travel.
 12. A system for use with a drilling systemin monitoring the speed of a pipe string while it is being run into orout of a well bore, comprising: transducer means constructed andarranged for translating the linear speed of a pipe string being movedby traveling block means into a direct current electrical input signalrepresentative of such speed, traveling block means for moving a pipemeans linearly with respect to a borehole, comparison means coupled tosaid transducer means for receiving the input signals from saidtransducer means for comparing such signals to a preset electricalsignal value in said comparison means for providing first output signalswhenever such input signals are below said preset signal value by apredetermined magnitude or second output signals whenever such inputsignals are above said preset signal by a predetermined magnitude, firstand second alarm indicator means coupled to said comparison means forreceiving respectively such first and second output signals and forproducing an indication in response to an output signal.
 13. Apparatusfor use in a drilling system where a string of pipe is moved into or outof a borehole, said apparatus including means for producing inputelectrical signals as a function of the actual linear speed of a stringof pipe moved relative to a borehole, means for moving a string of pipelinearly relative to a borehole, alarm means coupled to said inputelectrical signal means for providing an indication whenever a string ofpipe is moved relative to a borehole with an actual linear speed whichexceeds a predetermined linear speed limit value, said alarm meansincluding preset means for selectively establishing a predeterminedlinear speed limit value by selective adjustment of an electricalparameter in said alarm means, means for correlating input electricalsignals from said input electrical signal means to such electricalparameter in said alarm means and for providing output electricalsignals whenever such input electrical signals and such presetelectrical parameter in said preset means reach a predeterminedcorrelation, and means coupled to said correlating means for receivingsaid output signals and for producing a physiological indication inresponse thereto.
 14. A system for use in a drilling system formonitoring the speed of a pipe string while it is being run into or outof a well bore, comprising: transducer means constructed and arrangedfor translating the linear speed of a pipe string being moved bytraveling block means into direct current electrical input signalsrepresentative of such speed, traveling block means for moving a stringof pipe relative to a borehole, electrical comparison means forreceiving input signals from said transducer means and for comparingsuch signals to a preset electrical signal value and for providing firstoutput signals whenever said input signals are less than said presetsignal by a predetermined magnitude and for providing second outputsignals whenever said input signals are greater than said preset signalby a predetermined magnitude, first and second alarm means respectivelyfor producing alarm signals, indicator means for providing indicationsof proper operation, means coupled to said comparison means forsupplying an actuating signal to said indicator means whenever saidinput signal is less than said predetermined magnitude, and saidsupplying means being actuatable by said first output signal forsupplying an actuating signal to said first alarm means and beingactuatable by said second output signal for supplying an actuatingsignal to said second alarm means.